1st piece of advice: return your tint to get a refund or take it to a tint person or shop and have them do it for you
cool cheap things:
dodge charger, magnum, 300c, and challanger wheels all fit on intrepids, check your local craigslist you can usually get a set for pretty cheap and people are always selling them because they got DUBS on there chargers n what not
tinting your tailights is also a cheap cool thing (not with window tinting though)
painting your brake calipers is also pretty sweet
if you want a pretty engine bay, cleaning up your engine and painting your air plenum is a couple bucks and a hour worth of work and looks nice! also, installing a cold air intake will run you around 80 bucks and adds a nice sound!